The Avocado or “Persea Americana” is originally from South America and first recorded in New Zealand around 1915, although some earlier settlers tried to grow it, without much luck. The commercial scale orchards we see today started in the 1970’s. In its early days it was known by a few names, Avocado Pear, Alligator Pear and in the military it was called, Subaltern’s butter or Midshipman’s butter. Loaded with good fats, a protein and minerals the avocados are almost a perfect food and now a staple to our diet.
A subtropical plant that has adapted well in many parts of the country and they are not difficult to grow once you have satisfied a few of their particular needs.
Where you plant needs careful consideration, avocadoes will tolerate a wide range of soils, but they will not tolerate poorly drained soils. Root rot or Phytopthera is its most common problem, foliage becomes pale and sparse and the tree dies. There is no cure for this fungus disease other than ensuring that you plant in a very free draining position and the addition of gypsum to the soil surrounding the tree will help combat this problem The position also needs to receive maximum sunlight hours, protection from strong winds and although the trees become hardier to frost as they grow they need protection when they are young.
Prepare the ground in advance; adding compost and blood and bone to the soil, if you think the soil is a little heavy, apply some Gypsum as well. Gypsum improves the soil structure without changing its ph and can be applied every few years as it is beneficial in the protection of root rot. Handle the trees very carefully as you plant, the roots are easily damaged. Stake if necessary, do this as you plant and before you fill the hole in.
Avocadoes have a well develop major root system as well as a system of feeder roots that sit just below the surface of the soil. Don’t cultivate around these roots and during the summer mulch with pea straw to retain moisture, protect and feed the roots. Keep the mulch away from the truck to reduce the chance of encouraging any bark diseases. Water well especially in its first few years and during flowering, a lack of water during this period will affect the setting of the fruit.
Annual pruning is not required, your overall aim is to produce a well balanced tree with an even spread of branches. Prune to remove any inwards facing, dead or unproductive branches. Eventually you may want to prune to reduce some height or if the branches are shading other plants. If you decide to give a mature tree a heavy prune, be aware that this can stop them fruiting for a couple of years until they recover. On average trees produce fruit from 3 to 4 years old and only in small numbers with the harvest increasing in each successive year.
There are varying opinions on the amount of fertilising that the avocado trees require and it depends on your soil type. But as rule of thumb nitrogen is the most required nutrient and this can be applied every 5-6 months, always watering in well after application. The best indicator if you are stuck though will be your tree; yellowish leaves will be an indication of a nitrogen deficiency. But with all that said there are plenty of trees out there that have never been fertilised and produce plenty of fruit.
Fruit production will be affected by a change in the climate especially the cold.
Some trees will produce a lot of flowers, not all of them will develop into fruit, the same goes for fruit, not all will fully develop and the tree will shed the excess.
Occasionally some defoliation can happen, this is because the tree is diverting its energy from the leaves to fruiting and it will correct itself.
Borer is an issue for the trees, it is easily spotted as the wood will often weep and the branch will produce poorly. Prune off the affected wood and seal all cuts with pruning paste. Check your citrus trees as they are also affected borer and will be helping to spread the insect.
Avocadoes trees carry both male and female flowers, so it doesn’t need another tree to pollinate it, although more than one tree can improve the fruit set and the quantity. They are pollinated by bees; a poor season for the bees will effect fruit production.
When picking the fruit use scissors and leave a little part of the stem attached, this will fall off as the fruit ripens.